KR102362364B1 - Liquid crystal display apparatus - Google Patents

Abstract

a liquid crystal panel, a first polarizing plate disposed on a light emitting surface of the liquid crystal panel, and a second polarizing plate disposed on a light incident surface of the liquid crystal panel, wherein the first polarizing plate includes a first polarizer and light output of the first polarizer a first protective film of the first polarizer disposed on the surface, wherein when the absorption axis of the first polarizer is 0°, the slow axis of the first protective film of the first polarizer is -5° to +5°, The second polarizer includes a second polarizer and a first protective film of the second polarizer disposed on a light incident surface of the second polarizer, and when an absorption axis of the second polarizer is 0°, the second polarizer of the second polarizer 1 The slow axis of the protective film is to form a -5 ° to +5 °, a liquid crystal display is provided.

Description

Liquid crystal display device {LIQUID CRYSTAL DISPLAY APPARATUS}

The present invention relates to a liquid crystal display device.

The liquid crystal display includes a liquid crystal panel and polarizing plates disposed on both sides of the liquid crystal panel. The liquid crystal display operates by diffusing and emitting light transmitted from the side in addition to the light transmitted through the front while the light emitted from the light source is emitted through the liquid crystal panel. Therefore, the luminance and contrast ratio of the light emitted from the side is inevitably lowered compared to the light emitted from the front.

In order to increase the contrast ratio and luminance from the side, there is a technique for adding a pattern layer capable of diffusing light to a polarizing plate or for diffusing light before the light passes through the liquid crystal panel. However, adding a pattern layer is cumbersome and complicated because it requires a process of forming a separate pattern layer when manufacturing a polarizing plate.

Background art of the present invention is described in Korean Patent Publication No. 10-2013-0040227 and the like.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a liquid crystal display capable of improving a side contrast ratio.

Another object of the present invention is to provide a liquid crystal display capable of improving luminance in white mode and significantly lowering luminance in black mode.

Another object of the present invention is to provide a liquid crystal display device capable of improving the lateral contrast ratio even with an economical and simple process.

One aspect of the present invention is a liquid crystal display device.

1. A liquid crystal display device includes a liquid crystal panel, a first polarizer disposed on a light exit surface of the liquid crystal panel, and a second polarizer plate disposed on a light incident surface of the liquid crystal panel, wherein the first polarizer includes a first polarizer and the and a first protective film of the first polarizer disposed on the light exit surface of the first polarizer, wherein when the absorption axis of the first polarizer is 0°, the slow axis of the first protective film of the first polarizer forms an absorption axis of -5° to +5° with the absorption axis of the first polarizer, and the second polarizer includes a second polarizer and a first protective film of the second polarizer disposed on a light incident surface of the second polarizer, , when the absorption axis of the second polarizer is 0°, the slow axis of the first protective film of the second polarizer is -5° to +5° with the absorption axis of the second polarizer.

In 2.1, the slow axis of the first protective film of the first polarizer is 0° with the absorption axis of the first polarizer, and the slow axis of the first protective film of the second polarizer is 0° with the absorption axis of the second polarizer can achieve

In 3.1-2, the slow axis of the first protective film of the first polarizer and the slow axis of the first protective film of the second polarizer may be 85° to 95°.

In 4.1-3, the first protective film of the first polarizer may have an in-plane retardation Re of 5,000 nm to 11,000 nm at a wavelength of 550 nm.

In 5.1-4, the first protective film of the second polarizer may have an in-plane retardation Re of 5,000 nm to 11,000 nm at a wavelength of 550 nm.

In 6.1-5, in the liquid crystal display, the absolute value of the difference in the in-plane retardation Re at a wavelength of 550 nm between the first protective film of the first polarizer and the first protective film of the second polarizer of Equation 1 is 0 nm to 500 nm can

[Equation 1]

|Re(I) - Re(II)|

(In Formula 1, Re(I) is the in-plane retardation Re (unit: nm) at a wavelength of 550 nm of the first protective film of the first polarizer,

Re(II) is the in-plane retardation Re (unit: nm) at a wavelength of 550 nm of the first protective film of the second polarizer.

In 7.1-6, the first protective film of the first polarizer and the first protective film of the second polarizer are each made of at least one resin selected from among polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, and polybutylene naphthalate. formed film.

In 8.1-7, the first polarizer further includes a second protective film of the first polarizer disposed on the light incident surface of the first polarizer, and the second polarizer plate is disposed on the light exit surface of the second polarizer A second protective film of the second polarizer may be further included.

In 9.8, the second protective film of the first polarizer may have an in-plane retardation Re of 10 nm to 300 nm at a wavelength of 550 nm.

In 10.8, when the absorption axis of the first polarizer is 0°, an angle between the fast axis of the second protective film of the first polarizer and the absorption axis of the first polarizer may be +0.03° to +0.2°.

In 11.8, the second protective film of the second polarizer may have an in-plane retardation Re of 10 nm to 200 nm at a wavelength of 550 nm.

In 12.8, when the absorption axis of the second polarizer is 0°, an angle between the fast axis of the second protective film of the second polarizer and the absorption axis of the second polarizer may be +0.03° to +0.2°.

In 13.1-12, the liquid crystal panel may include liquid crystal in VA mode.

In 14.1-13, the liquid crystal display may further include a light source disposed on the incident surface of the second polarizing plate, and the light source may include at least one of a white LED light source, a quantum dot light source, and a metal fluoride red phosphor light source. .

The present invention provides a liquid crystal display capable of improving a side contrast ratio.

The present invention provides a liquid crystal display capable of improving the luminance in the white mode and significantly lowering the luminance in the black mode.

The present invention provides a liquid crystal display device capable of improving side contrast ratio even with an economical and simple process.

1 is a cross-sectional view of a liquid crystal display device according to an embodiment of the present invention.
2 is a schematic diagram showing the absorption axis of the first polarizer, the slow axis of the first protective film of the first polarizer, the absorption axis of the second polarizer, and the slow axis of the first protective film of the second polarizer in the liquid crystal display of the present invention. .

Hereinafter, embodiments of the present application will be described in more detail with reference to the accompanying drawings. However, the technology disclosed in the present application is not limited to the embodiments described herein and may be embodied in other forms. However, the embodiments introduced herein are provided so that the disclosed content may be thorough and complete, and the spirit of the present application may be sufficiently conveyed to those skilled in the art. In order to clearly express the components of each device in the drawings, the sizes such as widths and thicknesses of the components are slightly enlarged. In a plurality of drawings, the same reference numerals refer to substantially the same components.

In this specification, "upper" and "lower" are defined based on the drawings, and depending on the perspective of the city, "upper" may be changed to "lower" and "lower" to "upper", and "on" or What is referred to as “on” may include cases where other structures are interposed in the middle as well as immediately above. On the other hand, reference to "directly on" or "immediately on" or "directly forming" refers to no intervening other structures such as intermediates.

In the present specification, the "in-plane retardation (Re)" of the polarizer protective film is represented by the following formula A, the "thickness direction retardation (Rth)" is represented by the following formula B, and "the degree of biaxiality (NZ)" is the following formula C is denoted as:

[Formula A]

Re = (nx - ny) x d

[Formula B]

Rth = ((nx + ny)/2 - nz) x d

[Formula C]

NZ = (nx - nz)/(nx - ny)

(In Formulas A to C, nx, ny, and nz are refractive indices in the slow axis direction, fast axis direction, and thickness direction of the polarizer protective film, respectively, at a wavelength of 550 nm, and d is the thickness of the polarizer protective film (unit: nm) ).

When describing a range in the present specification, "X to Y" means "X or more and Y or less" (X≤ and ≤Y).

When describing an angle in the present specification, a clockwise direction is indicated by "+" and a counterclockwise direction by "-" based on 0°.

The inventors of the present invention have tried to invent a liquid crystal display device having a remarkably high lateral contrast ratio through an economical and simple process. As a result, the inventor of the present invention includes a first polarizer disposed on the light exit surface of the liquid crystal panel and a second polarizer plate disposed on the light incidence surface of the liquid crystal panel, and the first polarizer includes the first polarizer and light output of the first polarizer When the first protective film of the first polarizer disposed on the surface is included and the absorption axis of the first polarizer is 0°, the slow axis of the first protective film of the first polarizer is -5° to +5 to the absorption axis of the first polarizer °, the second polarizer includes the second polarizer and the first protective film of the second polarizer disposed on the light incident surface of the second polarizer, and when the absorption axis of the second polarizer is 0°, the first of the second polarizer It was confirmed that the above-described effect can be obtained by forming the slow axis of the protective film at -5° to +5° with the absorption axis of the second polarizer.

In particular, in the liquid crystal display of the present invention, at least one of the first polarizing plate and the second polarizing plate does not include a contrast-ratio improving layer such as a pattern layer, so that the absorption axis of the polarizer is not added without additional manipulation such as adding a pattern layer among the polarizing plates. It is possible to remarkably increase the side contrast ratio and side luminance only by a simple operation of adjusting the angle between the slow axis of the polarizer and the protective film of the polarizer. In addition, the effect of the present invention can be obtained only by adjusting the angle between the absorption axis of the polarizer and the slow axis of the polarizer protective film and the cutting process in the process of cutting the polarizing plate with the polarizer protective film adhered to one side of the polarizer before adhering to the liquid crystal panel. By improving the luminance in the white mode and lowering the luminance in the black mode with an economical and simple process, the side contrast ratio can be significantly increased. The contrast improvement layer may refer to a pattern layer including a conventional high refractive index layer and a low refractive index layer and a pattern portion formed between the high refractive index layer and the low refractive index layer known to those skilled in the art, but is not limited thereto.

Hereinafter, a liquid crystal display device of the present invention will be described with reference to FIGS. 1 and 2 .

Referring to FIG. 1 , the liquid crystal display includes a liquid crystal panel 100 , a first polarizing plate 200 disposed on an upper surface (a light emitting surface of the liquid crystal panel) of the liquid crystal panel 100 , and a lower surface of the liquid crystal panel 100 . and a second polarizing plate 300 disposed on the (light incident surface of the liquid crystal panel).

Although not shown in FIG. 1 , the first polarizing plate 200 and the second polarizing plate 300 may be adhered to the liquid crystal panel 100 by an adhesive layer, respectively. The pressure-sensitive adhesive layer may be prepared by a conventional pressure-sensitive adhesive known to those skilled in the art. The adhesive layer has no substantial effect on the side brightness and side contrast ratio.

The first polarizer 200 includes a first polarizer 210 , a first protective film 220 of the first polarizer disposed on an upper surface (a light exit surface of the first polarizer) of the first polarizer 210 , and the first polarizer and a second protective film 230 of the first polarizer disposed on the lower surface of the 210 (the light incident surface of the first polarizer). The second polarizer 300 includes a second polarizer 310 , a first protective film 330 and a second polarizer of the second polarizer disposed on a lower surface (light incident surface of the second polarizer) of the second polarizer 310 . and a second protective film 320 of the second polarizer disposed on the upper surface of the 310 (the light exit surface of the second polarizer).

Referring to FIG. 2 , the first polarizer 210 has an absorption axis 211 of the first polarizer, and the first protective film 220 of the first polarizer has a slow axis 221 . When the absorption axis 211 of the first polarizer is 0°, the angle formed by the slow axis 221 of the first protective film 220 of the first polarizer and the absorption axis 211 of the first polarizer (hereinafter, “ the first angle") is between -5° and +5°.

Referring to FIG. 2 , the second polarizer 310 has an absorption axis 311 of the second polarizer, and the first protective film 330 of the second polarizer 310 has a slow axis 331 . When the absorption axis 311 of the second polarizer 310 is 0°, the slow axis 331 of the first protective film 330 of the second polarizer 310 is the absorption axis 311 of the second polarizer 310 and The angle formed (hereinafter, may also be referred to as a “second angle”) is -5° to +5°.

By satisfying both the ranges of the first angle and the second angle described above, the contrast ratio and luminance may be increased in the entire side, for example, a polar angle of 60° and an azimuth angle.

In one embodiment, the first angle may be -3° to +3°, specifically -1° to +1°, more specifically -0.5° to +0.5°, 0°.

In one embodiment, the second angle may be -3° to +3°, specifically -1° to +1°, more specifically -0.5° to +0.5°, 0°.

The first angle and the second angle may be implemented by aligning the absorption axis of the polarizer and the slow axis of the polarizer first protective film at the above-described angles when manufacturing the first polarizing plate and the second polarizing plate, respectively, and then cutting them. The adhesion is not particularly limited, but may be adhered by roll-to-roll of the polarizer and the polarizer first protective film.

The first protective film 220 of the first polarizer 210 is disposed on the light exit surface of the first polarizer. In the present invention, the angle between the absorption axis of the first polarizer 210 and the slow axis of the first protective film disposed on the light exit surface of the first polarizer is adjusted. When the angle between the fast axis of the second protective film of the first polarizer disposed on the light incident surface of the first polarizer and the absorption axis of the first polarizer was adjusted, the effect of improving the side contrast ratio and the side luminance was weak.

The first protective film 220 of the first polarizer may have an in-plane retardation Re of 5,000 nm to 11,000 nm at a wavelength of 550 nm. When the first polarizing plate is applied within the above range, there may be an effect of improving rainbow mura, and when the first angle of the present invention is obtained, it may help to improve the side contrast ratio and side brightness. Preferably, the in-plane retardation Re at a wavelength of 550 nm of the first protective film may be 6,000 nm to 10,000 nm, 6,000 nm to 9,000 nm, or 7,000 nm to 9,000 nm.

The manufacturing method of the first protective film 220 of the first polarizer is not particularly limited as long as it has a slow axis while having the above-described in-plane retardation Re.

For example, the first protective film 220 of the first polarizer may be manufactured by uniaxial stretching or biaxial stretching. In one embodiment, the first protective film of the first polarizer may be an MD uniaxially oriented film or a TD uniaxially oriented film. In another embodiment, the first protective film of the first polarizer may be an MD and TD sequential or simultaneous biaxially oriented film. Preferably, the first protective film of the first polarizer is a TD uniaxially oriented film, and it is easy to secure the above-described in-plane retardation Re. The stretching may be performed by at least one of dry stretching or wet stretching. In dry stretching, the stretching temperature may be 20°C to 50°C, preferably 40°C to 50°C, and in wet stretching, the stretching temperature may be 20°C to 50°C, preferably 40°C to 50°C. The draw ratio may be 2 to 7 times, preferably 3 to 6 times.

In one embodiment, the thickness direction retardation Rth of the first protective film 220 of the first polarizer at a wavelength of 550 nm may be 5,000 nm to 11,000 nm. When the first polarizing plate is applied within the above range, there may be an effect of improving rainbow mura, and when the first angle of the present invention is obtained, it may help to improve the side contrast ratio and side brightness. Preferably, the thickness direction retardation Rth at a wavelength of 550 nm may be 7,000 nm to 9,000 nm, or 8,000 nm to 9,000 nm.

The first protective film 220 of the first polarizer may have a degree of biaxiality NZ of 1.3 to 1.7 at a wavelength of 550 nm. When the first polarizing plate is applied within the above range, there may be an effect of improving rainbow mura, and when the first angle of the present invention is obtained, it may help to improve the side contrast ratio and side brightness. Preferably, the degree of biaxiality NZ at a wavelength of 550 nm may be 1.4 to 1.6.

The first protective film 330 of the second polarizer is disposed on the light incident surface of the second polarizer. In the present invention, the angle between the absorption axis of the second polarizer 310 and the slow axis of the first protective film 330 disposed on the light incident surface of the second polarizer is adjusted. When the angle between the fast axis of the second protective film of the second polarizer disposed on the light exit surface of the second polarizer and the absorption axis of the second polarizer was adjusted, the effect of improving the side contrast ratio and the side luminance was weak.

The first protective film 330 of the second polarizer may have an in-plane retardation Re of 5,000 nm to 11,000 nm at a wavelength of 550 nm. When the second polarizing plate is applied within the above range, there may be an effect of improving rainbow mura, and when the second angle of the present invention is obtained, it may help to improve the side contrast ratio and side brightness. Preferably, the in-plane retardation Re at a wavelength of 550 nm may be 6,000 nm to 10,000 nm, 6,000 nm to 9,000 nm, and 7,000 nm to 9,000 nm.

The manufacturing method of the first protective film 330 of the second polarizer is not particularly limited as long as it has a slow axis while having the above-described in-plane retardation Re. For example, the first protective film 330 of the second polarizer may be manufactured by making the stretching temperature, the stretching ratio, or the stretching method the same or different in the above-described manufacturing method for the first protective film of the first polarizer. Preferably, the first protective film of the second polarizer may be a TD uniaxially oriented film.

In one embodiment, the thickness direction retardation Rth of the first protective film 330 of the second polarizer may be 5,000 nm to 11,000 nm at a wavelength of 550 nm. In the above range, there may be an improvement effect of rainbow mura, and when the second angle of the present invention is obtained, it may help to improve the side contrast ratio and side brightness. Preferably, the thickness direction retardation Rth at a wavelength of 550 nm may be 7,000 nm to 9,000 nm, or 8,000 nm to 9,000 nm.

The first protective film 330 of the second polarizer may have a degree of biaxiality NZ of 1.3 to 1.7 at a wavelength of 550 nm. In the above range, there may be a rainbow mura improvement effect, and when the first angle of the present invention is obtained, it may help to improve the side contrast ratio and side brightness. Preferably, the degree of biaxiality NZ at a wavelength of 550 nm may be 1.4 to 1.6.

The first protective film 220 of the first polarizer may have the same or different in-plane retardation Re compared to the first protective film 330 of the second polarizer. For example, the absolute value of the difference in the in-plane retardation Re at a wavelength of 550 nm between the first protective film of the first polarizer and the first protective film of the second polarizer of Equation 1 is 0 nm to 500 nm, preferably 0 nm to 100 nm, more Preferably, it may be 0 nm to 50 nm: in the above range, it may be economically effective to improve the side contrast ratio and side brightness.

[Equation 1]

|Re(I) - Re(II)|

(In Formula 1, Re(I) is the in-plane retardation Re (unit: nm) at a wavelength of 550 nm of the first protective film of the first polarizer,

Re(II) is the in-plane retardation Re (unit: nm) at a wavelength of 550 nm of the first protective film of the second polarizer.

The slow axis 221 of the first protective film of the first polarizer 210 and the slow axis 331 of the first protective film of the second polarizer 310 are 85° to 95°, preferably 88° to 92° , more preferably 89.5° to 90.5°, and most preferably 90°. Within the above range, there may be an effect of improving the rainbow mura, and when the first angle and the second angle of the present invention are obtained, there may be an effect in improving the side contrast ratio and the side brightness.

The thickness of the first protective film 220 of the first polarizer and the first protective film 330 of the second polarizer may be the same or different. For example, the first protective film of the first polarizer and the first protective film of the second polarizer may have a thickness of 10 μm to 500 μm, preferably 40 μm to 300 μm, more preferably 40 μm to 100 μm. can In the above range, it may be used for a polarizing plate and may be easy to implement in-plane retardation.

The first protective film 220 of the first polarizer and the first protective film 330 of the second polarizer may include a resin film made of the same or different materials. For example, the first protective film of the first polarizer and the first protective film of the second polarizer include a cellulose ester-based resin containing triacetylcellulose (TAC), etc., a cyclic type containing amorphous cyclic polyolefin (COP), etc. Polyester resin, polyether including polyolefin resin, polycarbonate resin, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), polybutylene naphthalate (PBN), etc. Poly(meth)acrylate-based resins, polyvinyl alcohol-based resins including sulfone-based resins, polysulfone-based resins, polyamide-based resins, polyimide-based resins, acyclic-polyolefin-based resins, polymethyl methacrylate resins, and the like , a polyvinyl chloride-based resin, and a film formed of at least one of a polyvinylidene chloride-based resin, but is not limited thereto. Preferably, the first protective film of the first polarizer and the second protective film of the second polarizer are polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate (PBT), and polybutylene naphthalate, respectively. By using a polyester-based resin film containing such as, the moisture permeability of the protective film is low, and high durability can be realized.

Although not shown in FIG. 1 , the first protective film 220 of the first polarizer may be adhered to the first polarizer 210 by an adhesive layer, and the first protective film 330 of the second polarizer may be attached to the second polarizer ( 310) by an adhesive layer. The adhesive layer may be prepared by a conventional adhesive known to those skilled in the art.

The second polarizer 310 polarizes the light incident from the light source and emits it to the liquid crystal panel. The second polarizer may include a polyvinyl alcohol-based polarizer manufactured by uniaxially stretching a polyvinyl alcohol-based film, or a polyene-based polarizer manufactured by dehydrating a polyvinyl alcohol-based film. The second polarizer may have a thickness of 5 μm to 40 μm, for example, 5 μm to 10 μm. Within the above range, it can be used for a polarizing plate.

The first polarizer 210 polarizes the light incident from the liquid crystal panel and emits it toward the first protective film of the first polarizer. The first polarizer may include a polyvinyl alcohol-based polarizer manufactured by uniaxially stretching a polyvinyl alcohol-based film, or a polyene-based polarizer manufactured by dehydrating a polyvinyl alcohol-based film. The first polarizer may have the same or different thickness than the second polarizer. For example, the first polarizer may have a thickness of 5 μm to 40 μm, for example, 5 μm to 10 μm. Within the above range, it can be used for a polarizing plate.

When the absorption axis 211 of the first polarizer is 0°, the angle between the absorption axis 211 of the first polarizer and the absorption axis 311 of the second polarizer is 85° to 95°, preferably 87° to 93°, more preferably 90°. In the above range, it is possible to increase the blocking efficiency of the light incident from the light source.

Referring back to FIG. 1 , the first polarizer 200 includes a second protective film 230 of the first polarizer 210 disposed on the light incident surface of the first polarizer 210 . The second protective film 230 of the first polarizer is disposed opposite to the first protective film of the first polarizer to prevent warping when the first polarizer is left for a long time at high temperature and/or high temperature and high humidity of the first polarizer or screen quality of the liquid crystal display device can be improved

The second protective film 230 of the first polarizer may have an in-plane retardation Re of 10 nm to 300 nm, preferably 10 nm to 150 nm, and more preferably 10 nm to 100 nm at a wavelength of 550 nm. In the above range, it is possible to increase the light efficiency of the first polarizer and increase the effect of increasing the side contrast ratio of the liquid crystal display.

The second protective film 230 of the first polarizer may have a thickness direction retardation Rth of 10 nm to 300 nm, preferably 10 nm to 150 nm at a wavelength of 550 nm. In the above range, it is possible to increase the light efficiency and increase the effect of increasing the side contrast ratio of the liquid crystal display.

The second protective film 230 of the first polarizer may have a degree of biaxiality NZ of 2.5 to 3.0, preferably 2.6 to 3.0, more preferably 2.7 to 2.9 at a wavelength of 550 nm. In the above range, it is possible to increase the light efficiency and increase the effect of increasing the side contrast ratio of the liquid crystal display.

The second protective film 230 of the first polarizer may also be a stretched film as described above in the first protective film of the first polarizer. The second protective film of the first polarizer may be the above-described MD uniaxially oriented film, TD uniaxially oriented film, or MD and TD biaxially oriented film. Preferably, the second protective film of the first polarizer may be an MD and TD biaxially oriented film.

The second protective film 230 of the first polarizer also has a slow axis and a fast axis.

When the absorption axis 211 of the first polarizer is 0°, the angle between the fast axis of the second protective film 230 of the first polarizer and the absorption axis 211 of the first polarizer is +0.03° to +0.2°, preferably +0.03° to +0.15°, more preferably 0°. Within the above range, polarization efficiency may be high, and there may be an effect of increasing the contrast ratio of the liquid crystal display panel.

The second protective film 230 of the first polarizer is a cellulose ester-based resin including triacetyl cellulose (TAC), a cyclic polyolefin-based resin including an amorphous cyclic polyolefin (COP), polycarbonate-based resin, polyethylene Polyester-based resins including terephthalate and polyethylene naphthalate, polyethersulfone-based resins, polysulfone-based resins, polyamide-based resins, polyimide-based resins, acyclic-polyolefin-based resins, polymethyl methacrylate resins, etc. It may include, but is not limited to, a film formed of at least one of poly(meth)acrylate-based resin, polyvinyl alcohol-based resin, polyvinyl chloride-based resin, and polyvinylidene chloride-based resin, including, but not limited to. Preferably, the second protective film of the first polarizer may increase the durability of the first polarizer by using a cyclic polyolefin-based resin film containing amorphous cyclic polyolefin (COP) or the like.

The second protective film 230 of the first polarizer may have a thickness of 10 μm to 500 μm, preferably 40 μm to 300 μm, and more preferably 40 μm to 100 μm. In the above range, it may be used for a polarizing plate and may be easy to implement in-plane retardation.

The second polarizer 300 includes a second protective film 320 of the second polarizer disposed on the light exit surface of the second polarizer. The second protective film of the second polarizer is disposed opposite to the first protective film of the second polarizer to prevent warping or improve the screen quality of the liquid crystal display when the second polarizer is left for a long time at high temperature and/or high temperature and high humidity. can

The second protective film 320 of the second polarizer may have an in-plane retardation Re of 10 nm to 300 nm at a wavelength of 550 nm, preferably 10 nm to 150 nm, and more preferably 10 nm to 100 nm. In the above range, it is possible to increase the light efficiency of the second polarizer and increase the effect of increasing the side contrast ratio of the liquid crystal display.

The second protective film 320 of the second polarizer may have a thickness direction retardation Rth of 10 nm to 300 nm, preferably 10 nm to 150 nm at a wavelength of 550 nm. In the above range, it is possible to increase the light efficiency and increase the effect of increasing the side contrast ratio of the liquid crystal display.

The second protective film 320 of the second polarizer may have a degree of biaxiality NZ of 2.5 to 3.0, preferably 2.6 to 3.0, preferably 2.7 to 2.9 at a wavelength of 550 nm. In the above range, it is possible to increase the light efficiency and increase the effect of increasing the side contrast ratio of the liquid crystal display.

The second protective film 320 of the second polarizer may also be a stretched film as described above in the first protective film of the first polarizer. The second protective film of the second polarizer may be the above-described MD uniaxially oriented film, TD uniaxially oriented film, or MD and TD biaxially oriented film. Preferably, the second protective film of the second polarizer may be an MD and TD biaxially oriented film.

The second protective film 320 of the second polarizer also has a slow axis and a fast axis.

When the absorption axis of the second polarizer is 0°, the angle between the fast axis of the second protective film of the second polarizer and the absorption axis of the second polarizer is +0.03° to +0.2°, preferably +0.03° to +0.15 °, more preferably 0 °. Within the above range, polarization efficiency may be high, and there may be an effect of increasing the contrast ratio of the liquid crystal display panel.

The second protective film 320 of the second polarizer may be a film of the same or different material from the second protective film of the first polarizer. For example, the second protective film of the second polarizer is a cellulose ester-based resin containing triacetyl cellulose (TAC), etc., a cyclic polyolefin-based resin containing amorphous cyclic polyolefin (COP), etc., a polycarbonate-based resin, Polyester-based resins including polyethylene terephthalate and polyethylene naphthalate, polyethersulfone-based resins, polysulfone-based resins, polyamide-based resins, polyimide-based resins, acyclic-polyolefin-based resins, polymethyl methacrylate resins It may include, but is not limited to, a film formed of at least one of poly(meth)acrylate-based resin, polyvinyl alcohol-based resin, polyvinyl chloride-based resin, and polyvinylidene chloride-based resin including, but not limited to. Preferably, the second protective film of the second polarizer may increase the durability of the second polarizer by using a cyclic polyolefin-based resin film containing amorphous cyclic polyolefin (COP) or the like.

The second protective film 320 of the second polarizer may have the same or different thickness as the second protective film 230 of the first polarizer. For example, the second protective film of the second polarizer may have a thickness of 10 μm to 500 μm, preferably 40 μm to 300 μm, and more preferably 40 μm to 100 μm. In the above range, it may be used for a polarizing plate and may be easy to implement in-plane retardation.

Although not shown in FIG. 1 , the second protective film of the first polarizer may be adhered to the first polarizer by an adhesive layer, and the second protective film of the second polarizer may be adhered to the second polarizer by the adhesive layer. The adhesive layer may be formed of a conventional adhesive known to those skilled in the art.

The liquid crystal panel 100 receives the polarized light incident from the second polarizer and emits it to the first polarizer. The liquid crystal panel includes a liquid crystal layer, and the liquid crystal in the liquid crystal layer implements a screen by changing the orientation when the electric field is turned on or off. Although not shown in FIG. 1 , the liquid crystal panel may include a liquid crystal layer, a first substrate disposed on one surface of the liquid crystal layer, and a second substrate disposed on the other surface of the liquid crystal layer. The liquid crystal panel may further include a color filter, TFT, or the like to improve screen quality.

The liquid crystal panel 100 may be in a TN, STN, IPS, or VA liquid crystal mode according to a liquid crystal type in the liquid crystal layer. Preferably, the liquid crystal panel may include a liquid crystal layer in VA liquid crystal mode.

The liquid crystal display may include a light source on the lower surface of the second polarizer, that is, on the light incident surface of the first protective film of the second polarizer disposed on the light incident surface of the second polarizer among the second polarizers. The light source may include a light source having a continuous emission spectrum. For example, the light source is a white LED (White LED) light source, a quantum dot (QD, quantum dot) light source, a metal fluoride red phosphor light source, specifically, a KSF (K ₂ SiF ₆ :Mn ⁴⁺ ) phosphor or KTF (K ₂ TiF ₆ : Mn ⁴⁺ ) a phosphor-containing light source and the like.

The liquid crystal display may further include a light guide plate, a diffusion plate, a light collecting sheet, and the like between the light source and the second polarizing plate.

Hereinafter, the configuration and operation of the present invention will be described in more detail through preferred embodiments of the present invention. However, this is presented as a preferred example of the present invention and cannot be construed as limiting the present invention in any sense.

Example One

(1) Manufacture of first polarizing plate

A polyvinyl alcohol film (PS60, Kuraray, thickness: 60 μm) was stretched 3 times at 60° C., iodine was adsorbed, and then stretched 2.5 times in an aqueous boric acid solution at 56° C. to prepare a polarizer (thickness: 25 μm).

A polyethylene terephthalate (PET) film (thickness: 80 μm TA044, Toybo Corporation) having an in-plane retardation Re at a wavelength of 550 nm in Table 1 below was adhered to the light emission surface of the polarizer with an adhesive. A cyclic olefin polymer (COP) film (in-plane retardation Re: 52 nm at a wavelength of 550 nm, thickness: 52 μm, ZB12, Zeon Corporation) was attached to the light incident surface of the polarizer with an adhesive to prepare a first polarizing plate. In this case, when the absorption axis of the polarizer in the first polarizer is 0°, the angle between the absorption axis of the polarizer and the slow axis of the PET film is 0°. The angle between the fast axis of the second protective film of the first polarizer and the absorption axis of the first polarizer was adjusted from +0.03° to +0.2°.

(2) Preparation of the second polarizing plate

A polarizer (thickness: 25 μm) was prepared by stretching a polyvinyl alcohol film (PS60, Kuraray, thickness: 60 μm) 3 times at 60° C., adsorbing iodine, and then stretching it 2.5 times in an aqueous boric acid solution at 40° C.

A polyethylene terephthalate (PET) film (thickness: 80 μm, TA044, Toybo Corporation) having an in-plane retardation Re at a wavelength of 550 nm in Table 1 below was adhered to the light incident surface of the polarizer with an adhesive. A cyclic olefin polymer (COP) film (in-plane retardation Re: 52 nm at a wavelength of 550 nm, thickness: 52 μm, ZB12, Zeon Corporation) was attached to the light emitting surface of the polarizer with an adhesive to prepare a second polarizing plate. In this case, when the absorption axis of the polarizer in the second polarizer is 0°, the angle between the absorption axis of the polarizer and the slow axis of the PET film is 0°. The angle between the fast axis of the second protective film of the second polarizer and the absorption axis of the second polarizer was adjusted from +0.03° to +0.2°.

(3) Manufacture of liquid crystal display device

The prepared first polarizing plate was adhered to the light exit surface of a liquid crystal panel (Samsung Display LCD Cell, LSY460HN01) having a liquid crystal layer in VA mode, and the prepared second polarizing plate was adhered to the light incident surface of the liquid crystal panel. In this case, the angle formed between the absorption axis of the polarizer of the first polarizer plate and the absorption axis of the polarizer of the second polarizer plate was 90°. A liquid crystal display was manufactured by disposing a white LED light source (WLED light source) as a light source on the lower surface of the second polarizing plate.

Example 2

In Example 1, as a first protective film for the first polarizer, a PET film having an in-plane retardation Re of 6600 nm at a wavelength of 550 nm (thickness: 60 μm, TA044, Toybo Corporation), as a first protective film for the second polarizer, in-plane retardation at a wavelength of 550 nm A liquid crystal display device was manufactured in the same manner as in Example 1, except that a PET film having Re of 6600 nm (thickness: 60 μm, TA044, Toybo Corporation) was used.

Example 3 to Example 4

In Example 1, the angle between the absorption axis of the first polarizer among the first polarizers and the slow axis of the first protective film of the first polarizer (first angle), the absorption axis of the second polarizer among the second polarizers and the second polarizer 1 A liquid crystal display was manufactured in the same manner as in Example 1, except that the angle (second angle) between the slow axes of the protective film was changed as shown in Table 1 below.

Example 5 to Example 6

In Example 2, the angle between the absorption axis of the first polarizer among the first polarizers and the slow axis of the first protective film of the first polarizer (first angle), the absorption axis of the second polarizer among the second polarizers and the second polarizer 1 A liquid crystal display was manufactured in the same manner as in Example 2, except that the angle (second angle) between the slow axes of the protective film was changed as shown in Table 2 below.

comparative example Lesson 1 comparative example 3

In Example 1, the angle between the absorption axis of the first polarizer among the first polarizers and the slow axis of the first protective film of the first polarizer (first angle), the absorption axis of the second polarizer among the second polarizers and the second polarizer 1 A liquid crystal display was manufactured in the same manner as in Example 1, except that the angle (second angle) between the slow axes of the protective film was changed as shown in Table 1 below.

comparative example 2, comparative example 4, comparative example 5

In Example 2, the angle between the absorption axis of the first polarizer of the first polarizer and the slow axis of the first protective film of the first polarizer (first angle), the absorption axis of the second polarizer among the second polarizer plate and the second polarizer A liquid crystal display was manufactured in the same manner as in Example 2, except that the angle (second angle) between the slow axes of the first protective film was changed as shown in Table 2 below.

For the liquid crystal display devices of Examples and Comparative Examples, a white screen of White Full 255 scale was driven using an LCD pattern generator of SPTEC. From the front, luminance in white mode and luminance in black mode were measured using ELDIM's EZ CONTRAST XW 886 luminance meter, and the contrast ratio was calculated as the ratio of luminance in white mode to luminance in black mode. Luminance in white mode and luminance in black mode were measured in the same manner as above at polar angles 60° and azimuth angles 45°, 135°, 225° and 315° in the oblique direction. Contrast ratio was calculated as a ratio of luminance, and the calculated contrast ratio and luminance in white mode are shown in Tables 1 and 2 below.

In Example 1, Example 3, Example 4, and Comparative Example 3, the contrast ratio and the luminance ratio were respectively the contrast ratio for Comparative Example 1 and the contrast ratio in Examples 1, 3, 4, and 3 for the luminance. , was calculated as the ratio of increase or decrease in luminance. In Example 2, Example 5, Example 6, Comparative Example 4, and Comparative Example 5, the contrast ratio and the luminance ratio were the contrast ratio for Comparative Example 2, Example 2 for the luminance, Example 5, Example 6, and Comparative Example 2, respectively. In Example 4 and Comparative Example 5, it was calculated as the ratio of increase or decrease in contrast ratio and luminance.

comparative example Example One 3 4 One 3 first polarizer first angle
(°) +90 +90 +5 0 -5 Re(nm) 8500 8500 8500 8500 8500 second polarizer second angle
(°) +90 0 +5 0 -5 Re(nm) 8500 8500 8500 8500 8500 (60°, 45°) contrast ratio 74.13 74.26 107.25 89.82 108.12 contrast ratio - 0.18% 44.69% 21.18% 45.87% luminance 63 79 74 84 79 luminance ratio - 26% 18% 34% 26% (60°, 135°) contrast ratio 76.83 73.13 112.17 83.36 108.22 contrast ratio - -4.82% 45.99% 8.49% 40.85% luminance 68 79 77 82 73 luminance ratio - 16% 14% 21% 7% (60°, 225°) contrast ratio 75.50 71.99 110.68 88.53 107.54 contrast ratio - -4.65% 46.59% 17.26% 42.43% luminance 65 78 73 80 75 luminance ratio - 19% 11% 23% 15% (60°, 315°) contrast ratio 67.86 67.54 103.38 79.45 102.00 contrast ratio - -0.47% 52.35% 17.08% 50.32% luminance 64 78 76 86 73 luminance ratio - 23% 19% 35% 14%

comparative example Example 2 4 5 5 2 6 first polarizer first angle
(°) +90 +90 0 +5 0 -5 Re(nm) 6600 6600 6600 6600 6600 6600 second polarizer second angle
(°) +90 0 +90 +5 0 -5 Re(nm) 6600 6600 6600 6600 6600 6600 (60°, 45°) contrast ratio 67.68 56.75 58.00 105.12 78.26 108.59 contrast ratio - -16% -14% 55% 16% 60% luminance 66 77 71 75 83 81 luminance ratio - -8% 8% 14% 25% 22% (60°, 135°) contrast ratio 68.32 59.40 60.47 107.22 80.15 106.23 contrast ratio - -13% -11% 57% 17% 55% luminance 61 76 65 78 81 73 luminance ratio - 16% 7% 29% 33% 20% (60°, 225°) contrast ratio 70.98 55.65 59.21 109.35 78.14 107.78 contrast ratio - -22% -17% 54% 10% 52% luminance 66 75 70 76 81 75 luminance ratio - 25% 6% 15% 23% 14% (60°, 315°) contrast ratio 65.66 55.92 57.23 103.08 74.37 104.75 contrast ratio - -15% -13% 57% 13% 60% luminance 62 76 66 78 80 76 luminance ratio - 14% 6% 26% 29% 23%

*1st angle: the angle between the absorption axis of the polarizer and the slow axis of the PET film when the absorption axis of the polarizer in the first polarizer is 0°

*Second angle: the angle between the absorption axis of the polarizer and the slow axis of the PET film when the absorption axis of the polarizer in the second polarizer is 0°

As shown in Tables 1 and 2, the liquid crystal display device of the present invention can improve side contrast ratio and side luminance. On the other hand, the liquid crystal display of the comparative example that is out of the first angle and the second angle of the present invention cannot improve the side contrast ratio.

Simple modifications or changes of the present invention can be easily carried out by those of ordinary skill in the art, and all such modifications or changes can be considered to be included in the scope of the present invention.

Claims (14)

a liquid crystal panel, a first polarizing plate disposed on a light exit surface of the liquid crystal panel, and a second polarizing plate disposed on a light incident surface of the liquid crystal panel,
The first polarizer includes a first polarizer and a first protective film of the first polarizer disposed on the light exit surface of the first polarizer, and when the absorption axis of the first polarizer is 0°, 1 A slow axis of the protective film forms an absorption axis of the first polarizer and -5° to +5°,
The second polarizer includes a second polarizer and a first protective film of the second polarizer disposed on a light incident surface of the second polarizer, and when an absorption axis of the second polarizer is 0°, the second polarizer of the second polarizer 1 The slow axis of the protective film forms an absorption axis of the second polarizer at -5° to +5°,
The first protective film of the first polarizer has an in-plane retardation Re of 5,000 nm to 11,000 nm at a wavelength of 550 nm,
The first protective film of the second polarizer has an in-plane retardation Re of 5,000 nm to 11,000 nm at a wavelength of 550 nm,
The first polarizer further includes a second protective film of the first polarizer disposed on the light incident surface of the first polarizer,
The second polarizer further comprises a second protective film of the second polarizer disposed on the light exit surface of the second polarizer,
When the absorption axis of the first polarizer is 0°, the angle between the fast axis of the second protective film of the first polarizer and the absorption axis of the first polarizer is +0.03° to +0.2°,
When the absorption axis of the second polarizer is 0°, the angle between the fast axis of the second protective film of the second polarizer and the absorption axis of the second polarizer is +0.03° to +0.2°, the liquid crystal display .
According to claim 1, wherein the slow axis of the first protective film of the first polarizer forms 0° with the absorption axis of the first polarizer, and the slow axis of the first protective film of the second polarizer is the absorption axis of the second polarizer and 0° to form a liquid crystal display device.
The liquid crystal display device of claim 1 , wherein a slow axis of the first protective film of the first polarizer and a slow axis of the first protective film of the second polarizer form an angle of 85° to 95°.
delete delete The absolute value of the difference of the in-plane retardation Re at a wavelength of 550 nm between the first protective film of the first polarizer and the first protective film of the second polarizer of Equation 1 below is 0 nm to 500 nm in the liquid crystal display device which is a liquid crystal display device:
[Equation 1]
|Re(I) - Re(II)|
(In Formula 1, Re(I) is the in-plane retardation Re (unit: nm) at a wavelength of 550 nm of the first protective film of the first polarizer,
Re(II) is the in-plane retardation Re (unit: nm) at a wavelength of 550 nm of the first protective film of the second polarizer.
According to claim 1, wherein the first protective film of the first polarizer and the first protective film of the second polarizer is at least one resin of polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, and polybutylene naphthalate, respectively. A liquid crystal display device comprising a film formed of
delete The liquid crystal display device of claim 1 , wherein the second protective film of the first polarizer has an in-plane retardation Re of 10 nm to 300 nm at a wavelength of 550 nm.
delete The liquid crystal display device of claim 1, wherein the second protective film of the second polarizer has an in-plane retardation Re of 10 nm to 300 nm at a wavelength of 550 nm.
delete The liquid crystal display device of claim 1 , wherein the liquid crystal panel includes liquid crystal in VA mode.
The liquid crystal display device of claim 1, further comprising a light source disposed on the incident surface of the second polarizing plate, wherein the light source comprises at least one of a white LED light source, a quantum dot light source, and a metal fluoride red phosphor light source. phosphorus, liquid crystal display.

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